JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<body>
	<main role="main">
		<section id="left">
      <header>
        <h1>Left Side</h1>
      </header>
      <article>
        <input type="button" id="refresh" value="Refresh" />
        <textarea></textarea>
      </article>
		</section>
	</main>
</body>

CSS

/*
reset.css
*/
html, body, div, span, applet, object, iframe,
h1, h2, h3, h4, h5, h6, p, blockquote, pre,
a, abbr, acronym, address, big, cite, code,
del, dfn, em, img, ins, kbd, q, s, samp,
small, strike, strong, sub, sup, tt, var,
b, u, i, center,
dl, dt, dd, ol, ul, li,
fieldset, form, label, legend,
table, caption, tbody, tfoot, thead, tr, th, td,
article, aside, canvas, details, embed,
figure, figcaption, footer, header, hgroup,
menu, nav, output, ruby, section, summary,
time, mark, audio, video {
  margin: 0;
  padding: 0;
  border: 0;
  font-size: 100%;
  font: inherit;
  vertical-align: baseline;
}

html, body {
  height: 100%;
  width: 100%;
}

html {
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;
  box-sizing: border-box;
}

*, *:before, *:after {
  -moz-box-sizing: inherit;
  -webkit-box-sizing: inherit;
  box-sizing: inherit;
}

body{
  background-color: red;
}

body, main, section, article, textarea{
  padding:1em;
}

main, section, article, textarea{
  height: 100%;
}

main, textarea {
  width: 100%;
}

main{
  background: yellow;
}

#left{
  width: 70%;
  background: blue;
}

input#refresh{
  margin: 10px 0;
}